However, it has got me thinking about different ways of developing web applications. In the Cappuccino model, the client programming is done in objective-j, and is - essentially - totally separate from the backend system. The client application has no connection with the server language. All that is required is the appropriate set of REST services. This is obviously very different from the Seaside model in which the client application is, almost, a by-product of the Squeak code.
But which approach is better? Cappuccino looks like an excellent development framework. A lot of basic OS X code (written in Objective-c) can be run, almost completely unchanged, in objective-j. And, perhaps best of all, the documentation is very good. This is achieved partly through the efforts of 280 North, but also because the Cocoa docs match up very well.
On the other hand, Seaside offers much better development tools and a very different way of working. I don't know enough about each approach to really form a conclusion, yet. But, it is nice to be spoilt for choice :-)